The present application relates generally to semiconductor processing and relates particularly to a substrate cleaning processes.
Fabrication of integrated circuits and semiconductor devices can involve many different types of processing techniques. Such techniques generally involve patterning a substrate and using the pattern to make various sacrificial and/or permanent structures. For example, photolithography can be used to create patterned layers using a thin layer of radiation-sensitive material, such as photoresist. This radiation-sensitive layer is transformed into a patterned mask that can be used to etch or transfer a pattern into an underlying layer on a substrate. Thus the patterned layer of photoresist can act as a mask for directional (anisotropic) etching of one or more underlying layers. To overcome challenges in photolithography image transfer, a patterned photoresist (functioning as a mask), can be used to create another mask in an underlying material with significantly different etch selectivity, this material is commonly referred to as a hardmask. Creating a hardmask can be beneficial because a given target underlying layer to be etched can respond to an etch chemistry that might simultaneously etch photoresist material, which would render a given photoresist relief pattern essentially ineffective to be used as a mask for some materials to be etched. Fabrication of integrated circuits and semiconductor devices can be a cyclical process of depositing materials, modifying materials, patterning materials, and removing materials. It is common to have a need to remove one type of material (such as a hardmask) without removing a second type of material, such as a patterned underlying layer. Various cleaning processes can be implemented to selectively remove or clean materials off of a given substrate. Such cleaning processes can include both wet cleaning techniques (such as reactive liquid chemicals) and dry cleaning techniques (such as plasma-based cleaning) using particular chemistries and/or physical mechanisms to clean materials off of a substrate.